INF-306 HTML5 Application Development Questions and Answers

First drop-down: navigator.geolocation

Second drop-down: navigator.geolocation

Third drop-down: getCurrentPosition(showLocation)

The correct API object is navigator.geolocation because browser-based geographic location is exposed through the Geolocation API, not through window.location. window.location represents the current page URL and navigation state; it does not provide latitude or longitude. The first selection checks whether the browser supports geolocation by evaluating navigator.geolocation. Inside the block, the same object must be used to request the user’s current position. The correct method is getCurrentPosition(showLocation), which requests the device’s current location and passes a position object to the callback function when the location is available. The callback then reads position.coords.latitude and position.coords.longitude and displays those values with alert(). The alternatives that pass window.location are incorrect because they provide page-location information rather than geographic coordinates. The alternatives that call showLocation(...) directly are also incorrect because the browser must first retrieve the actual position object. References/topics: Geolocation API, navigator.geolocation, getCurrentPosition(), callback functions, latitude and longitude.

The correct transformation functions are matrix() and skew(). CSS transformations are applied with the transform property and accept transform functions that alter an element’s rendered appearance in two-dimensional or three-dimensional space. MDN defines < transform-function > as a data type representing a transformation that can rotate, resize, distort, or move an element in 2D or 3D space. The matrix() function is valid because it defines a homogeneous two-dimensional transformation matrix, allowing translation, scaling, rotation, and skewing effects to be represented numerically in one function. The skew() function is also valid because it explicitly skews an element on the 2D plane. scroll() is not a CSS transform function; scrolling is handled through overflow behavior or scrolling APIs. move() is also not a valid CSS transform function; the standard transform function for movement is translate(). References/topics: CSS3 transforms, transform property, 2D transformation functions, matrix(), skew().

==========

First box: minlength

Second box: maxlength

Third box: required

The correct validation attributes are minlength, maxlength, and required. The input must accept a category abbreviation that is either two or three characters long. The minlength= " 2 " attribute enforces the lower boundary by preventing submission when the entered text contains fewer than two characters. The maxlength= " 3 " attribute enforces the upper boundary by preventing the user from entering more than three characters into the field. Since the question states that the input is mandatory, the required attribute must also be included. required is a Boolean validation attribute, so it does not need a value; its presence alone makes the field required before the form can be submitted. Together, these attributes configure basic HTML5 constraint validation directly in markup without requiring JavaScript. The completed input therefore requires a value, rejects values shorter than two characters, and limits the value to no more than three characters. References/topics: HTML5 form validation, minlength, maxlength, required, text input constraints, mandatory form fields.

First blank: display: grid;

Second blank: grid-template-columns: auto auto auto auto;

Third blank: grid-gap: 10px;

The layout shown is a CSS Grid layout with eight items arranged into four equal-width columns and two rows. The first required declaration is display: grid;, which turns the .grid-container element into a grid container. The second declaration is grid-template-columns: auto auto auto auto;, which defines four columns, matching the four visible boxes in each row: Mickey, Minnie, Luna, and George on the first row, then Bilbo, Bella, Madeline, and Groucho on the second row. The third declaration is grid-gap: 10px;, which creates spacing between the grid cells, matching the visible blue gaps around each item. The background-color: #336699; creates the blue container background, while padding: 10px; adds space around the outer edge of the grid. The child rule .grid-container > div styles each grid item with a light background, centered text, padding, and larger font size.

First drop-down: flex boxes

Second drop-down: background-size

Third drop-down: cover

The correct layout mechanism is responsive flex boxes because the content changes from a vertical mobile arrangement to a wider multi-column layout as space becomes available. Flexbox supports this behavior naturally through flexible item sizing and wrapping, often without needing explicit media queries for every screen size. The header image must fill its visible header region on both mobile and desktop. The correct CSS property for controlling how a background image scales inside its container is background-size. The correct value is cover, because background-size: cover scales the image so that the entire container is covered while preserving the image’s aspect ratio. This prevents distortion, although some cropping can occur when the image and container have different aspect ratios. contain would preserve the full image but may leave empty space. auto would use the image’s intrinsic size and would not reliably fill the header area. background-attachment, background-clip, and background-repeat do not control image scaling.

The correct positioning method is static. In CSS, position: static is the default positioning behavior for elements. A statically positioned element remains in the normal document flow, meaning it is laid out according to the order of the markup and directly follows preceding elements unless another layout rule changes that flow. MDN defines static positioning as placing the element according to the normal flow of the document, with top, right, bottom, left, and z-index having no effect. This matches the requirement that the element always directly follows the previous default-positioned element and does not depend on viewport characteristics. absolute removes the element from normal flow and positions it relative to a containing block. fixed also removes it from normal flow and positions it relative to the viewport. sticky starts in normal flow but changes behavior relative to a scrolling ancestor when a threshold is crossed. References/topics: CSS positioning, normal document flow, static positioning, viewport-independent layout.

==========

The correct methods are setItem(), removeItem(), and clear(). The HTML5 Web Storage API exposes localStorage as a persistent key-value storage object for the current origin. Data stored in localStorage remains available after page reloads and browser restarts unless it is explicitly removed or cleared. setItem(key, value) stores a value under a named key or updates the value if the key already exists. removeItem(key) deletes one specific key-value pair from storage. clear() removes all key-value pairs from the storage object for that origin. These methods are part of the standard Storage interface used by both localStorage and sessionStorage. write is not a Web Storage method; it is associated with document-writing behavior, not application state storage. cookie is also incorrect because cookies are a separate browser storage mechanism accessed through document.cookie, not a method of localStorage. References/topics: Web Storage API, localStorage, Storage interface, application state, persistent key-value data.

==========

The correct property is clear. In CSS layout, float removes an element from the normal inline flow and positions it to the left or right, allowing following content to wrap beside it. The clear property controls whether an element may be positioned next to preceding floated elements or must be moved below them. MDN defines clear as the property that sets whether an element must be moved below floating elements that precede it. Typical values include left, right, both, and none, allowing the developer to block floats on one or both sides. display controls the formatting behavior of an element, such as block, inline, flex, or grid. float creates the floating behavior; it does not prevent other floats from appearing beside an element. position controls positioning schemes such as static, relative, absolute, fixed, or sticky. Therefore, only clear directly defines the sides where adjacent floating elements are not permitted. References/topics: CSS floats, content flow, clearing floated elements, layout positioning.

==========

The two likely causes are undersized touch targets and overlapping input regions. Touch input is less spatially precise than mouse input because the contact area of a finger is larger and less exact than a pointer cursor. Microsoft’s touch-target guidance states that interactive UI elements must be large enough for users to access accurately, and recommends a target size around 7.5 mm square, approximately 40 × 40 pixels on a 135 PPI display. Earlier Microsoft touch-design guidance similarly emphasizes that controls must be appropriately sized for touch and identifies approximately 9 mm as a minimum targeting area. Therefore, small input buttons may fail to trigger because the user is not actually hitting the active target area. Overlap is also a valid cause: when two active regions occupy the same physical screen area, hit testing may route the touch to a different element, or the effective target area may be reduced. W3C accessibility guidance explicitly treats overlapping targets as reducing measurable target size unless the overlapping controls perform the same action. Event handlers themselves are not the defect; they are the normal mechanism for processing input. “Touch screen not initialized” is not a standard HTML5 application cause. References/topics: touch input, event handling, hit testing, target size, overlapping controls.

The correct setting is overflow: auto;. The CSS overflow property controls how content behaves when it does not fit inside an element’s padding box. The requirement has three parts: keep the text inside the element’s border, avoid unnecessary scrollbars, and avoid losing text. overflow: hidden clips overflowing content and does not provide a user-visible scrollbar, so text can become inaccessible. overflow: visible allows excess content to render outside the element’s box, failing the containment requirement. overflow: scroll makes the element scrollable, but user agents display scrollbars whether or not content is actually overflowing, which violates the requirement to avoid unneeded scrollbars. MDN describes overflow: auto as clipping overflow content at the padding box while allowing it to be scrolled into view, with scrollbars displayed only when content is actually overflowing. This makes auto the precise choice for a controlled text container. References/topics: CSS overflow, scroll containers, content clipping, layout flow, preserving overflowing content.

==========

First blank: img

Second blank: filter:

Third blank: grayscale(100%)

Fourth blank: blur(8px)

The correct CSS selector is img because the requirement applies the visual effect to gallery images. The correct property is filter:, not transform:, because CSS filters modify the rendered appearance of an element using image-processing effects such as blur, grayscale, opacity, brightness, contrast, and shadows. The filtered sample appears blurred and colorless, so the appropriate filter functions are grayscale(100%) and blur(8px). grayscale(100%) removes all color from the image, converting it to a black-and-white rendering. blur(8px) obscures visual details, making the image difficult to recognize until the protected or authorized state changes the styling. The filter keyword without a colon is not a valid CSS declaration in this context. brightness(40%) and opacity(50%) could further obscure an image, but they are not required to reproduce the shown filtered result. The final declaration is therefore filter: grayscale(100%) blur(8px);.

The correct value is column-reverse. The flex-direction property defines the main axis of a flex container and determines whether flex items are laid out horizontally, vertically, or in the reverse direction. column creates a vertical layout where items flow from the top of the container toward the bottom. If new content is appended after existing content, normal column layout places that new item later in the visual list, typically lower on the page. column-reverse preserves a vertical main axis but reverses the visual direction, so later items in the source order appear at the highest visual point of the list. This satisfies the requirement without using the order property on individual flex items. row and row-reverse are incorrect because they create horizontal layouts, not vertical lists. The reverse-direction flex values should be used deliberately because visual order can differ from DOM order, but for this exam scenario, column-reverse is the value that places newly appended vertical content at the top. References/topics: CSS flexbox, flex-direction, main axis, column layout, reverse visual flow.

==========

Media queries support responsive web design and allow different CSS rules to be applied at different screen sizes, device characteristics, or breakpoints. MDN describes media queries as a CSS mechanism for applying styles depending on media type and device or viewport characteristics, including width, height, resolution, and orientation. This is the foundation of responsive design because a page can adapt its layout for phones, tablets, laptops, and desktop displays without changing the HTML document. Breakpoints are the points where the design changes; MDN identifies them as the points where a media query is introduced to improve layout behavior across viewport sizes. Statement A is not generally correct because media queries are primarily a styling and layout mechanism, not a direct performance optimization. They can sometimes help avoid unsuitable layouts, but performance improvement is not their defining purpose. Statement D is incorrect because media queries are CSS rules; they do not execute or dynamically process JavaScript code. References/topics: responsive design, CSS media queries, viewport width, breakpoints, adaptive layout rules.

==========

The correct 2D transformation functions are matrix() and skew(). CSS transformations are applied through the transform property, which accepts transform functions that can move, rotate, scale, skew, or otherwise alter an element visually in two-dimensional or three-dimensional space. MDN describes the < transform-function > type as representing transformations that affect an element’s appearance and can operate in 2D or 3D space. The matrix() function is valid because it defines a homogeneous two-dimensional transformation matrix, allowing multiple transform effects to be represented in a single function. The skew() function is also valid because it distorts an element along the 2D plane. move() is not a CSS transform function; the standard movement function is translate(). scroll() is not a transform function; scrolling is controlled through overflow and scroll APIs. zoom() is not a CSS3 2D transform function. References/topics: CSS3 transforms, transform property, 2D transformation functions, matrix(), skew().

==========

The correct method is preventDefault(). During form submission, the browser’s default behavior is to submit the form to the target URL, which may navigate away from the current page or reload it. If the submitted data is invalid and the application must display custom error messages while preserving the entered values, the submit event handler should call event.preventDefault(). This cancels the default submit action, allowing the page to remain in place and the script to display validation feedback next to the relevant form controls. defaultPrevented is not the method to use; it is only a Boolean property that indicates whether preventDefault() has already been called. cancelable is also only informational; it tells whether the event’s default behavior can be canceled. abort is unrelated to form validation and does not provide the required control over form submission. References/topics: HTML5 form validation, custom validation messages, submit event, event cancellation, preserving form data.

First drop-down: datalist

Second drop-down: vehicles

Third drop-down: < /datalist >

The correct element is < datalist > because the interface requires a text input that provides selectable suggestions while still allowing the user to type. The < input > element uses list= " vehicles " , so it must be connected to a < datalist > element whose id is exactly vehicles. The id cannot be vehicle, because vehicle is already the input element’s own identifier and does not match the value used by the list attribute. The < option > elements inside the datalist define the suggested values: Motorcycle, Truck, Boat, Car, and Bicycle. ul, ol, and li are list-markup elements and do not create input suggestions. select would create a fixed dropdown list, but it would not match the editable input-with-suggestions behavior shown. The closing tag must match the opening datalist element, so the final selection is < /datalist > .

The correct answers are A and C because background-size: contain and background-size: cover are the CSS values that scale a background image in response to the size of the element or viewport. contain scales the background image as large as possible while preserving the entire image inside the background area. This prevents cropping and maintains the image’s aspect ratio, although empty space may appear if the container and image proportions differ. cover also preserves the aspect ratio, but scales the image until the entire background area is filled; this may crop part of the image, but it prevents empty space. Both values are commonly used in responsive design because the image automatically recalculates its rendered size as the page or element changes dimensions. initial resets the property to its default behavior and does not intentionally create responsive scaling. auto uses the image’s intrinsic dimensions or proportional automatic sizing, so it does not reliably adjust the graphic to different screen sizes in the way required. References/topics: responsive design, CSS background images, background-size, contain, cover, viewport-based scaling.

==========